Axle shaft disconnect assembly

ABSTRACT

A drive axle assembly comprises a carrier member having a trunnion outwardly extending from the carrier member, an output shaft axially outwardly extending from the carrier member, a differential assembly including a differential case supported for rotation within the carrier member and a side gear rotatably mounted about the output shaft, a clutch collar non-rotatably coupled thereto and configured to selectively drivingly engage the side gear, and an annular clutch actuator for axially moving the clutch collar between a first position and a second position. The clutch collar drivingly engages the side gear in power transmitting relationship in the first position, while the clutch collar is disengaged from the side gear in the second position.

BACKGROUND OF THE INVENTION

1. Field of the Invention

This invention relates to vehicle axle assemblies in general, and moreparticularly, to an axle disconnect assembly for an auxiliary drive axleassembly of a four-wheel drive motor vehicle.

2. Description of the Prior Art

Four-wheel drive vehicles which are operable in either a two-wheel drivemode or a four-wheel drive mode are known as part time four wheel drivevehicles, are well known in the prior art. It is also known to providethe part time four wheel drive vehicle with an axle disconnect (ordifferential disconnect) mechanism in a front (or sometimes rear) axleassembly. Various axle disconnect assemblies or mechanisms have beenproposed. These mechanisms in general have a number of moving parts, arefairly complex, and would be suitable only for installation onrelatively wide vehicles because of the space required.

Such axle disconnect mechanisms typically include a fluid motor(hydraulic, pneumatic or vacuum) and a shift fork assembly. The fluidmotor communicates with a fluid source that is usually controlled by atwo position solenoid valve. The fork shift assembly under control ofthe fluid motor controls the axial shifting of a clutch collar betweenpositions corresponding to coupled and uncoupled operating modes.

This conventional system has the drawback of an externally mountedactuator that requires considerable extra space particularly whenvehicle suspension travel is taken into account. The use of anexternally mounted actuator also necessitates the use of a fork shiftassembly which adds to the cost and complexity of the prior artarrangement exemplified by this system. Moreover, such prior art axledisconnect systems do not provide a modular arrangement necessary foreasy of manufacture, assembly and repair. Consequently these prior artarrangements are also complex and expensive to produce particularly whenthe difficulty of assembly is taken into account.

Moreover, the prior art axle designs typically include an axle shaftwith male splines connected to a side gear bore with female splines, toprevent relative rotation and transmit torque. For beam axles (or rigidaxles), shaft lateral movement is usually restrained by (A) the shaftbearing at the wheel end, or (B) a C-clip attached to the axle shaftinboard of the side gear. For independent axles, i.e. the axles allowingthe relative motion (or travel) between the left-hand and right-handouter axle shafts, the shaft lateral movement is usually restrained by acollapsing/expanding ring contained within grooves on the shaft O.D. andside gear bore I.D.; this method is utilized for independent axles tofacilitate shaft connection to the axle during the vehicle build. Tointegrate axle disconnect mechanisms within an independent axleassembly, the prior art methodology of axle shaft retention is notsatisfactory. C-clips and expanding rings cannot be used because theshaft and side gear must be capable of rotating independently indisconnect mode. The shaft cannot be retained exclusively at thewheelend, because the length of the shaft varies due to wheel travel andthe inboard plunging CV joint. Therefore, a new mechanism is required to(A) retain the shaft within the axle assembly, and (B) permit shaft toside gear relative rotation.

The need therefore exists for an axle disconnect assembly and an axleshaft retention in an independent axle assembly that are simple indesign, compact in construction and economical to package andmanufacture.

SUMMARY OF THE INVENTION

The present invention provides an improved drive axle assembly for amotor vehicle, including an axle disconnect mechanism.

In one aspect, the present invention discloses the drive axle assemblycomprising a carrier member including an outwardly extending trunnionhaving an opening therethrough, an output shaft axially outwardlyextending from the carrier member through the opening in the trunnion, adifferential assembly including a differential case supported forrotation within the carrier member and a side gear being rotatablymounted about the output shaft, a clutch collar disposed about theoutput shaft and non-rotatably coupled thereto and configured toselectively drivingly engage the side gear, and an annular clutchactuator mounted to the trunnion for axially moving the clutch collarbetween a first position in which the clutch collar drivingly engagesthe side gear and a second position in which the clutch collar isdisengaged from the side gear.

In another aspect, the present invention discloses the drive axleassembly comprising a carrier member, an output shaft axially outwardlyextending from the carrier member, a differential assembly including adifferential case supported for rotation within the carrier member and aside gear being rotatably mounted about the output shaft, a drive sleeverotatably mounted about the output shaft and non-rotatably coupled tothe side gear, a clutch collar disposed about the output shaft andnon-rotatably coupled thereto and configured to selectively drivinglyengage the drive sleeve, and a clutch actuator for axially moving theclutch collar between a first position in which the clutch collardrivingly engages the drive sleeve and a second position in which theclutch collar is disengaged from the drive sleeve.

In yet another aspect, the present invention discloses the drive axleassembly comprising a carrier member, an output shaft axially outwardlyextending from the carrier member, a differential assembly including adifferential case supported for rotation within by the carrier memberand a side gear being rotatably mounted about the output shaft, a shaftretention collar disposed about the output shaft between the side gearand said output shaft so that the side gear is rotatably mounted aboutthe shaft retention collar, a clutch collar disposed about the outputshaft and non-rotatably coupled thereto and configured to selectivelydrivingly engage the side gear, and an annular clutch actuator mountedto the trunnion for axially moving the clutch collar between a firstposition in which the clutch collar drivingly engages the side gear anda second position in which the clutch collar is disengaged from the sidegear.

Therefore, the present invention provides a novel axle shaft disconnectassembly for a drive axle of a motor vehicle that utilizes conventionalcasting and machining processes for a carrier member, a differentialcase, and an axle shaft, thus significantly reducing capital and toolingrequirements to implement for production.

BRIEF DESCRIPTION OF THE DRAWINGS

Other objects and advantages of the invention will become apparent froma study of the following specification when viewed in light of theaccompanying drawings, wherein:

FIG. 1 is a cross-sectional view of a drive axle assembly according to afirst exemplary embodiment of the present invention;

FIG. 2 is an exploded partial sectional view of the drive axle assemblyaccording to the first exemplary embodiment of the present inventionshowing in detail a trunnion of a carrier member and an end plate;

FIG. 3 is a partial sectional view of the drive axle assembly accordingto the first exemplary embodiment of the present invention in a first,engaged position;

FIG. 4 is a partial sectional view of the drive axle assembly accordingto the first exemplary embodiment of the present invention in a second,disengaged position;

FIG. 5 is an enlarged partial sectional view of the drive axle assemblyaccording to the first exemplary embodiment of the present inventionshowing in detail a side gear and a drive sleeve;

FIG. 6 is an enlarged partial sectional view of the drive axle assemblyaccording to the first exemplary embodiment of the present inventionshowing in detail a fluid-operated clutch actuator;

FIG. 7 is an exploded partial sectional view of the drive axle assemblyaccording to the first exemplary embodiment of the present inventionshowing an integrated fluid-operated actuator/end cap assembly;

FIG. 8 is a cross-sectional view of a drive axle assembly according to asecond exemplary embodiment of the present invention;

FIG. 9 is a partial sectional view of the drive axle assembly accordingto the second exemplary embodiment of the present invention in a first,engaged position;

FIG. 10 is a partial sectional view of the drive axle assembly accordingto the second exemplary embodiment of the present invention in a second,disengaged position;

FIG. 11 is an enlarged partial sectional view of the drive axle assemblyaccording to the second exemplary embodiment of the present inventionshowing in detail a side gear and a clutch collar;

FIG. 12 is a cross-sectional view of the drive axle assembly showing analternative structure of the differential carrier member according tothe second exemplary embodiment of the present invention;

DESCRIPTION OF THE PREFERRED EMBODIMENTS

The preferred embodiments of the present invention will now be describedwith the reference to accompanying drawing.

For purposes of the following description, certain terminology is usedin the following description for convenience only and is not limiting.The words such as “front” and “rear”, “left” and “right”, “inboard” and“outboard”, “inwardly” and “outwardly” designate directions in thedrawings to which reference is made. The words “smaller” and “larger”refer to relative size of elements of the apparatus of the presentinvention and designated portions thereof. The terminology includes thewords specifically mentioned above, derivatives thereof and words ofsimilar import. Additionally, the word “a”, as used in the claims, means“at least one”.

Referring now to FIGS. 1-4 of the drawings, an auxiliary drive axleassembly according to a first exemplary embodiment of the presentinvention, generally denoted by reference numeral 10, includes a hollowcarrier member 12 and a differential assembly 14 disposed within thecarrier member 12 and driven by a pinion gear (not shown in FIG. 1). Thedifferential assembly 14 includes a differential case 18 housing adifferential mechanism (or gearing) 20. The differential mechanism, asit understood in the mechanical art and hereinbelow, is a system ofgears capable of dividing the input torque of one input shaft betweentwo output shafts where rotation at different speeds is likely to occur,as in cornering. The differential case 18 of the differential assembly14 is rotatably supported within the carrier member 12 throughconventional first (left) and second (right) differential anti-frictionbearings 22, which are preferably of the tapered roller bearing type,for rotation about a central axis 24 of the carrier member 12. Thehollow carrier member 12 is preferably formed with various internalsurfaces which support the components of the drive axle assembly 10.Specifically, the carrier member 12 includes first and second oppositetrunnions 26 ₁ and 26 ₂, respectively, each having a generallycylindrical side opening 27 therethrough (shown in detail in FIG. 2)defining the central axis 24 of the carrier member 12. Each of the firstand second trunnions 26 ₁ and 26 ₂ outwardly extends opposite to theother from the carrier member 12 in the direction of the central axis24.

The drive axle assembly 10 further comprises first and second outputaxle shafts (or stub shafts) 28 ₁ and 28 ₂, respectively, coaxiallyoutwardly extending from the side openings 27 through the respectivefirst and second trunnions 26 ₁ and 26 ₂ of the carrier member 12 forrotation about the central axis 24. It will be appreciated that thefirst and second output shafts 28 ₁ and 28 ₂ outwardly extend from thedifferential case 18 substantially coaxially with the central axis 24 ofthe carrier member 12. The carrier member 12 further includes first andsecond opposite end caps 30 ₁ and 30 ₂, respectively, each fastened tothe corresponding trunnions 26 ₁ and 26 ₂ of the carrier member 12 (suchas by threaded fasteners 35) to close the openings 27 therein and ismounted about the corresponding output axle shaft 28 ₁ or 28 ₂ coaxiallytherewith. Moreover, each of the first and second end caps 30 ₁ and 30 ₂is sealed within the corresponding trunnions 26 ₁ and 26 ₂ of thecarrier member 12 by an O-ring 31. On the other hand, the first andsecond output axle shafts 28 ₁, and 28 ₂ rotatably support thecorresponding first and second end caps 30 ₁ and 30 ₂ throughantifriction roller bearings 33, such as needle bearings. Preferably,the first and second end caps 30 ₁ and 30 ₂ are substantiallystructurally identical.

Preferably, the drive axle assembly 10 according to the presentinvention is an independent drive axle assembly. It will be appreciatedthat in independent drive axle assembly (as opposed to a rigid driveaxle assembly) the carrier member is mounted to a frame or bodystructure of the motor vehicle such that the deflection (or verticaltravel) of one vehicle wheel is not directly transmitted to the carriermember. In other words, the independent drive axles allow the relativeangular (or vertical) motion (or travel) between the left-hand andright-hand outer axle shafts. Specifically, the stub shafts 28 ₁ and 28₂ are drivingly coupled to left-hand and right-hand outer axle shafts(not shown) connected to the vehicle driving wheels, through suitablecoupling means, such as constant-velocity (CV) joints (not shown)provided at the distal ends of the stub shafts 28 ₁ and 28 ₂. Typically,the independent drive axles are used in conjunction with independentsuspensions.

The differential mechanism 20, disposed centrally within thedifferential case 18, includes a pinion (or cross) shaft 32non-rotatably secured to the differential case 18, a pair of piniongears 34 rotatably and coaxially disposed upon the pinion shaft 32within the differential case 18, and first and second side gears 36 ₁and 36 ₂, respectively. The first and second side gears 36 ₁ and 36 ₂engage each of these pinion gears 34 and are disposed concentricallyabout the corresponding axle shafts 28 ₁ and 28 ₂, respectively. Thedifferential mechanism 20 conventionally provides a differentialrotation of the first side gear 36 ₁ relative to the second side gear 36₂. However, unlike the conventional differential assembly, each of theside gears 36 ₁ and 36 ₂ of the differential assembly 14 according tothe present invention is rotatably mounted about the correspondingoutput shafts 28 ₁ and 28 ₂ through first and second shaft retentioncollars 38 ₁ and 38 ₂, respectively.

Referring now to FIG. 5 of the drawings, the mounting arrangement of thefirst side gear 36 ₁ to an inward end of the first output shaft 28 ₁ isillustrated in detail. It will be appreciated that preferably themounting arrangements of the first and second side gears 36 ₁ and 36 ₂to an inward end of the corresponding first and second output shafts 28₁ and 28 ₂are substantially identical, as can be seen in FIG. 1. Asillustrated in detail in FIG. 5, a cylindrical inner peripheral surface40 of the first side gear 36 ₁ is adapted to pilot a complementarycylindrical outer peripheral surface 42 of the first shaft retentioncollar 38 ₁. The first shaft retention collar 38 ₁ is restrainedlaterally in the direction of the central axis 24 between thedifferential pinion shaft 32 and an annular shoulder 44 of the firstside gear 36 ₁. When the inward end of the first output shaft 28 ₁ isinstalled into the first shaft retention collar 38 ₁, an expandable snapring 46 locks the first output shaft 28 ₁ to the first shaft retentioncollar 38 ₁. As further shown in FIG. 5, the snap ring 46 is disposed incomplementary annular grooves 47 and 48 formed in the first output shaft28 ₁ and the first shaft retention collar 38 ₁, respectively. Moreover,an O-ring 55, preferably made of an appropriate elastomeric material,such as rubber, is mounted about the first output shaft 28 ₁ so as to becompressed between the first shaft retention collar 38 ₁ and the firstoutput shaft 28 ₁. The elastomeric O-ring 55 provides a frictionalengagement between the first shaft retention collar 38 ₁ and the firstoutput shaft 28 ₁ to restrain or prevent relative rotation between thefirst shaft retention collar 38 ₁ and the first output shaft 28 ₁, whileensuring relative rotation between the first side gear 36 ₁ and thefirst shaft retention collar 38 ₁. Preferably, the elastomeric O-ring 55is disposed in an annular groove formed in the first output shaft 28 ₁.This mechanism radially pilots the first output shaft 28 ₁ in the firstside gear 36 ₁, permits relative rotation between the first output shaft28 ₁ and the first side gear 36 ₁, and restrains the first output shaft28 ₁ within the carrier member 12.

The drive axle assembly 10 further comprises a first annular drivesleeve 50 ₁ rotatably mounted about the first output shaft 28 ₁coaxially therewith and non-rotatably coupled to the first side gear 36₁, and a second annular drive sleeve 50 ₂ rotatably mounted about thesecond output shaft 28 ₂ coaxially therewith and non-rotatably coupledto the second side gear 36 ₂. Preferably, the first (right) and second(left) drive sleeves 50 ₁ and 50 ₂ are structurally identical, thereforeonly the drive sleeve 50 ₁ is disclosed in details herein below. Thedrive axle assembly 10 also includes a first clutch (or disconnect)assembly 60 ₁ provided for selectively drivingly disconnecting orconnecting the first output shaft 28 ₁ to or from the first side gear 36₁, and a second clutch (or disconnect) assembly 60 ₂ provided forselectively drivingly disconnecting or connecting the second outputshaft 28 ₂ to or from the second side gear 36 ₂. Preferably, the first(right) and second (left) clutch assemblies 60 ₁ and 60 ₂ aresubstantially identical, both structurally and functionally (as shown inFIG. 1), therefore only one of the clutch assemblies 60 ₁ and 60 ₂ isdisclosed in details herein below.

As illustrated in FIGS. 3-6, the first clutch assembly 60 ₁ includes afirst sliding clutch collar 62 ₁ and a substantially annular firstfluid-operated clutch actuator 64 ₁ provided for axially driving(moving) the first clutch collar 62 ₁ between a first, engaged position(or mode) (FIG. 3) and a second, disengaged position (or mode) (FIG. 4).Specifically, in the first position, the first clutch collar 62 ₁drivingly engages the first side gear 36 ₁ in power transmittingrelationship (as shown in FIG. 3), while in the second position, thefirst clutch collar 62 ₁ is rotationally independent from the first sidegear 36 ₁. Preferably, the first clutch collar 62 ₁ of the first clutchassembly 60 ₁ is substantially identical to a second fluid-operatedclutch actuator assembly 64 ₂ of the second clutch assembly 60 ₂. Thefirst clutch collar 62 ₁ is disposed concentrically about the firstoutput shaft 28 ₁. Moreover, the first clutch collar 62 ₁ isnon-rotatably but slideably coupled to the first output shaft 28 ₁, suchas by a spline connection. Specifically, as illustrated in detail inFIG. 6, the first clutch collar 62 ₁ includes female splines 63 whichmate with complementary male splines 29 formed on the first output shaft28 ₁. The mating female and male splines 63 and 29, respectively, permitaxial motion of the first clutch collar 62 ₁ relative the first outputshaft 28 ₁ while inhibiting relative rotational motion therebetween.Preferably, the first fluid-operated clutch actuator 64 ₁ is a pneumaticactuator and may operate on pressurized air or, preferably, a vacuum toprovide linear travel of the first clutch collar 62 ₁. Actuators poweredby hydraulic fluid, electricity or other means, which are axiallydrivable between the first and second modes are equally suitable for usewith the instant invention.

The first drive sleeve 50 ₁, shown in detail in FIG. 5, is rotatablymounted about the first output shaft 28 ₁ concentrically therewith andis constantly non-rotatably (drivingly) coupled to the first side gear36 ₁, such as by a spline connection, so that the first clutch collar 62₁ is configured to selectively drivingly engage the first side gear 36 ₁through the first drive sleeve 50 ₁. More specifically, the first sidegear 36 ₁ has radially inwardly directed (or female) splines 37, whilethe first drive sleeve 50 ₁ has first radially outwardly directed (ormale) splines 52 complementary to and in mesh with the female splines 37of the first side gear 36 ₁ at an inner end 51 of the first drive sleeve50 ₁ and second radially outwardly directed (or male) splines 54complementary to the female splines 63 of the first clutch collar 62 ₁at an outer end 53 of the first drive sleeve 50 ₁. The mating male andfemale splines 54 and 63 of the first drive sleeve 50 ₁ and the firstclutch collar 62 ₁, respectively, permit axial motion of the firstclutch collar 62 ₁ relative the first drive sleeve 50 ₁.

In view of the above described similarities and in the interest ofsimplicity, the following discussion will sometimes use a referencenumeral in brackets without a letter to designate each of twosubstantially identical structures of the first and second trunnions 26₁ and 26 ₂, the first and second output shafts 28 ₁ and 28 ₂, the firstand second end caps 30 ₁ and 30 ₂, the first and second side gears 36 ₁and 36 ₂, the first and second drive sleeves 50 ₁ and 50 ₂, the firstand second clutch assemblies 60 ₁ and 60 ₂, the first and second clutchcollars 62 ₁ and 62 ₂, and the first and second fluid-operated clutchactuator assemblies 64 ₁ and 64 ₂, etc. For example, the referencenumeral [64] will be used when generically referring to both the firstand second fluid-operated clutch actuator assemblies 64 ₁ and 64 ₂rather than reciting two different reference numerals.

The vacuum-operated clutch actuator [64], illustrated in detail in FIG.6, includes an annular actuator housing defined by the end cap [30]mounted to the trunnion [26], and an annular spring-biased actuatorpiston 66 at least partially disposed within the actuator housing [30]and sealingly connected to the actuator housing [30] through bellows 68.Both the annular actuator housing [30] and the annular actuator piston66 of the vacuum-operated clutch actuator [64] are disposed about theoutput shaft [28] concentrically therewith. The end cap [30] is providedwith an annular mounting flange 39 (also shown in FIG. 2) axiallyinwardly extending into the opening 27 in the trunnion [26] so as todefine an open annular cavity in the end cap [30]. In turn, a space inthe annular end cap [30] delimited by the mounting flange 39 thereof andthe actuator piston 66, and sealed by the bellows 68 defines a fluidchamber (or, preferably, a vacuum chamber) 70 within the end cap [30].Therefore, the first fluid-operated clutch actuator 64 ₁ including thefirst end cap 30 ₁ as an integral part thereof defines a firstintegrated fluid-operated actuator/end cap assembly. In other words, theend cap [30] acts as a housing of the vacuum-operated clutch actuator[64]. Similarly, the second fluid-operated clutch actuator 64 ₂including the second end cap 30 ₂ as an integral part thereof defines asecond integrated fluid-operated actuator/end cap assembly.

The vacuum-operated clutch actuator [64] further includes a springmember, such as a wave spring 72, disposed in the vacuum chamber 70 fornormally biasing the actuator piston 66 toward the first, engagedposition of the clutch collar [62]. The annular spring-loaded actuatorpiston 66 is provided with an actuator arm (or shift fork) 67 formedintegrally with the actuator piston 66 to drivingly engage an annulargroove 69 formed on a radially outer peripheral surface of the clutchcollar [62] for axially moving the clutch collar [62] into and out ofdriving engagement with the drive sleeve [50] and, consequently, withthe side gear [36]. Preferably, the actuator piston 66 and the actuatorarm 67 are made homogeneously as a single part member. The actuator arm67 is designed to mate with the annular groove 69 in the clutch collar[62].

The vacuum chamber 70 of the vacuum-operated clutch actuator [64]communicates with a suitable external source of fluid pressure, such asan external vacuum source (not shown in FIGS. 1-6) via fluid passages(not shown in FIGS. 1-6) formed through the carrier member 28 and theactuator housing (end cap) [30], respectively, for connecting thevacuum-operated clutch actuator [64] to the external vacuum source suchas the engine manifold through a control valve (not shown in FIGS. 1-4).The integrated actuator/end cap assembly [64] communicates with theexternal vacuum source via an external fitting (not shown in FIGS. 1-4)for connecting the vacuum-operated clutch actuator [64] to the externalvacuum source. Moreover, the actuator housing [30] to axle shaft [28]sliding interface is sealed by a lip seal 90 non-rotatably mounted tothe actuator housing [30].

Operation of the drive axle assembly 10 incorporating the disconnectassembly [60] according to the instant invention is best understood byreference to FIGS. 3 and 4.

When a vacuum is not applied in the vacuum chamber 70 of thevacuum-operated clutch actuator [64], the actuator piston 66 is shiftedaxially inward toward the side gear [36], as shown in the FIG. 3, by thespring member 72. Consequently, the actuator arm 67 of the actuatorpiston 66 moves the clutch collar [62] so that the female splines 63 ofthe clutch collar [62] mesh with (drivingly engage) the complementarymale splines 54 of the drive sleeve [50], thus placing the disconnectassembly [60] in the first, engaged mode, as illustrated in FIG. 3, bydrivingly engaging the side gear [36] with the output shaft [28]. Thoseskilled in the art would appreciate that in the engaged mode of thedisconnect assembly 60, the side gear [46] is drivingly coupled to theoutput shaft [28] through the drive sleeve [50] and the clutch collar[62]. In this operational mode, torque can be transmitted from the sidegear [36] to the output shaft [28].

When a vacuum is applied in the vacuum chamber 70 of the vacuum-operatedclutch actuator [64], the actuator piston 66 is shifted axially outwardaway from the side gear [36] against the biasing force of the springmember 72. Consequently, the actuator arm 67 of the actuator piston 66moves the clutch collar [62] so that the female splines 63 of the clutchcollar [62] disengage from the complementary male splines 54 of thedrive sleeve [50], thus placing the disconnect mechanism [60] in thesecond, disengaged mode, as illustrated in FIG. 4. Those skilled in theart would appreciate that in the disengaged mode of the disconnectmechanism [60], the side gear [36] is disconnected (disengaged) from theoutput shaft [28]. In the disengaged mode, the output shaft [28] isrotationally independent from the side gear [36] and the othercomponents of the differential mechanism 40 and may freewheelindependently of another output shaft [28]. Moreover, in disconnectmode, the side gear [36] may be stationary while the output shaft [28]rotates due to tire rotation.

It should be noted that the changeover from the engaged mode to thedisengaged mode of the output shaft [28] or vice versa is quickly andconveniently accomplished remotely by means of an appropriate controlsystem associated with the vacuum-operated clutch actuator [64]. Theactivating control for the vacuum-operated clutch actuator [64] may thusbe located in a cab of the motor vehicle within the driver's reach.

FIGS. 8-10 illustrate a drive axle assembly 110 according to a secondexemplary embodiment of the present invention. Components, which areunchanged from the previous exemplary embodiments of the presentinvention, are labeled with the same reference characters. Components,which function in the same way as in the first exemplary embodiment ofthe present invention depicted in FIGS. 1-5 are designated by the samereference numerals to which 100 has been added, sometimes without beingdescribed in detail since similarities between the corresponding partsin the two embodiments will be readily perceived by the reader.

The drive axle assembly 110 according to the second exemplary embodimentof the present invention, shown in FIGS. 8-10, comprises a hollowdifferential carrier member 112 and a differential assembly 114 disposedwithin the carrier member 112 and driven by a pinion gear 16. Adifferential case 118 of the differential assembly 114 is rotatablysupported within the carrier member 112 through conventional first(left) and second (right) differential anti-friction bearings 22, whichare preferably of a tapered roller bearing type, for rotation about acentral axis 24 of the carrier member 112. The hollow carrier member 112is preferably formed with various internal surfaces which support thecomponents of the drive axle assembly 110. Specifically, the carriermember 112 includes first and second opposite trunnions 126 ₁ and 126 ₂,respectively, each having a generally cylindrical side opening 127therethrough defining the central axis 24 of the carrier member 112.Each of the first and second trunnions 126 ₁ and 126 ₂ outwardly extendsfrom the carrier member 112 in the direction of the central axis 24.

The drive axle assembly 110 further comprises first and second outputaxle shafts 128 ₁ and 128 ₂, respectively, coaxially outwardly extendingfrom the side openings 127 through the respective first and secondtrunnions 126 ₁ and 126 ₂ of the carrier member 112 for rotation aboutthe central axis 24. It will be appreciated that the first and secondoutput shafts 128 ₁ and 128 ₂ outwardly extend from the differentialcase 18 substantially coaxially with the central axis 24 of the carriermember 112.

Disposed centrally within the differential case 18 is a differentialmechanism (or gearing) 120. The differential mechanism 120 includes apinion (or cross) shaft 32 secured to the differential case 18, a pairof pinion gears 34 rotatably and coaxially disposed upon the pinionshaft 32 within the differential case 18, and first and second sidegears 136 ₁ and 146 ₂, respectively. The first and second side gears 136₁ and 146 ₂ engage each of these pinion gears 34 and are disposedconcentrically about the corresponding axle shafts 128 ₁ and 128 ₂,respectively. The differential mechanism 120 conventionally provides adifferential rotation of the first side gear 136 ₁ relative to thesecond side gear 136 ₂. However, unlike the conventional differentialassembly, each of the side gears 136 ₁ and 136 ₂ of the differentialassembly 114 according to the present invention is rotatably mountedabout the corresponding output shafts 128 ₁ and 128 ₂ through first andsecond shaft retention collars 138 ₁ and 138 ₂, respectively. It will beappreciated that preferably the mounting arrangements of the first andsecond side gears 136 ₁ and 136 ₂ to the corresponding first and secondoutput shafts 128 ₁ and 128 ₂ are substantially identical, as shown inFIG. 8. The carrier member 112 also includes appropriately locatedaccess opening conventionally sealed by removable cover 139 (shown inFIG. 8).

In the interest of simplicity, the following discussion will sometimesuse a reference numeral in brackets without a letter to designate eachof two substantially identical structures of the first and secondtrunnions 126 ₁ and 126 ₂, the first and second output shafts 128 ₁ and128 ₂, the first and second side gears 136 ₁ and 136 ₂, first and secondshaft retention collars 138 ₁ and 138 ₂ and other pairs of identicalcomponents of the drive axle assembly 110. For example, the referencenumeral [136] will be used when generically referring to both the firstand second side gears 136 ₁ and 136 ₂, rather than reciting twodifferent reference numerals.

Referring now to FIG. 11 of the drawings, the mounting arrangement ofthe side gear [136] to an inward end 131 of the output shaft [128] isillustrated in detail. As illustrated in FIG. 11, the shaft retentioncollar [138] is provided with inner (or female) splines 138 acomplementary to outer (or male) splines 129 provided at the inward end131 of the output shaft [128]. When assembled, the male splines 129 ofthe output shaft [128] drivingly engage the female splines 138 a of theshaft retention collar [138]. A cylindrical inner peripheral surface 140of the side gear [136] is adapted to pilot a complementary cylindricalouter peripheral surface 142 of the shaft retention collar [138]. Theshaft retention collar [138] is restrained laterally in the direction ofthe central axis 24 between the differential pinion shaft 32 and anannular shoulder 144 of the side gear [136]. When the inward end 131 ofthe output shaft [128] is installed into the shaft retention collar[138], an expandable snap ring 146 locks the output shaft [128] to theshaft retention collar [138]. As shown in FIG. 8, the snap ring 146 isdisposed in complementary annular grooves 147 and 148 formed in theoutput shaft [128] and the shaft retention collar [138], respectively.This mechanism radially pilots the output shaft [128] in the side gear[136], permits relative rotation between the output shaft [128] and theside gear [136], and restrains the output shaft [128] within the carriermember 112. Each of the side gears [136] also includes a hub portion 150having a plurality of axially outwardly extended coupling teeth 152formed on an annular, axially outwardly facing surface 151 thereof. Thecoupling teeth 152 of the side gear [136] are circumferentially (orangularly) spaced from each other.

The drive axle assembly 110 according to the second exemplary embodimentof the present invention further includes a first clutch (or disconnect)assembly 160 ₁ (as shown in FIGS. 8-10), provided for selectivelydrivingly disconnecting or connecting the first output shaft 128 ₁ to orfrom the first side gear 136 ₁, and a second clutch (or disconnect)assembly 160 ₂ (as shown in FIG. 8), provided for selectively drivinglydisconnecting or connecting the second output shaft 128 ₂ to or from thesecond side gear 136 ₂.

The first (right) and second (left) clutch assemblies 160 ₁ and 160 ₂are substantially structurally identical, both structurally andfunctionally, therefore, in the interest of simplicity, the referencenumeral [160] will be used when generically referring to both the firstand second clutch assemblies 160 ₁ and 160 ₂ herein below, rather thanreciting two different reference numerals.

The clutch assembly [160] includes a sliding clutch collar 162 (shown indetail in FIG. 11) and a substantially annular fluid-operated clutchactuator 164. The clutch collar 162 is disposed concentrically about theoutput shaft [128] and generally adjacent the inward end 131 of theoutput shaft [128]. Moreover, the clutch collar 162 is non-rotatably butslideably coupled to the output shaft [128], such as by a splineconnection. Specifically, the clutch collar 162 includes female splines163 which mate with complementary male splines 137 formed on the outputshaft [128]. The mating female and male splines 163 and 137 permitrelative axial motion between the clutch collar 162 and the output shaft[128] while inhibiting relative rotational motion therebetween. Theclutch collar 162 further includes a plurality of axially inwardlyextended coupling teeth 165 formed on an axially inwardly facing surface167 thereof. The coupling teeth 165 of the clutch collar 162 arecircumferentially (or angularly) spaced from each other, and arecomplementary to and engageable with the coupling teeth 152 of the sidegear [136]. Also, the clutch collar 162 is formed with an annular groove169 disposed about a periphery thereof.

The fluid-operated clutch actuator 164 is provided for axially drivingthe clutch collar 162. Preferably, the fluid-operated clutch actuator164 is a pneumatic actuator and may operate on pressurized air or,preferably, a vacuum to provide linear travel of the clutch collar 162between a first, engaged mode (FIG. 9) and a second, disengaged mode(FIG. 10). Actuators powered by hydraulic fluid, electricity or othermeans, which are axially drivable between the first and second modes areequally suitable for use with the instant invention. The vacuum-operatedclutch actuator 164 includes a substantially annular actuator housing130 defining a vacuum chamber 170 therein, and an annular spring-loadedactuator piston 166 slideably disposed within the actuator housing 130for axially moving the clutch collar 162 and is secured to the actuatorhousing 130 through bellows 168 so as seal the vacuum chamber 170.

Each of the actuator housings 130 of the vacuum-operated clutch actuator164 is rotatably mounted about the corresponding output axle shaft [128]coaxially therewith and is non-rotatably secured to the carrier member112 within the corresponding trunnion [126], such as by press fitting,so as to close the opening 127 therein. Moreover, the annular actuatorhousing 130 is sealed within the corresponding pension [126] of thecarrier member 112 by O-rings 131. On the other hand, the output axleshaft [128] rotatably supports the corresponding actuator housing 130through an antifriction roller bearing 133, such as needle bearing.Therefore, the actuator housing 130 of the fluid-operated clutchactuator assembly 164 not only defines the vacuum chamber 170, but alsoacts (functions) as an end cap of the trunnion [126] closing the opening127 therein. Accordingly, the fluid-operated clutch actuator assembly164 including the actuator housing 130 as an integral part thereofdefines an integrated fluid-operated actuator/end cap assembly.

As further illustrated in FIGS. 8-10, an expandable snap ring, such asC-ring, 135 limits the axially outward travel of the actuator housing130 so as to retain the actuator housing 130 within the correspondingtrunnion [126] of the carrier member 112. Preferably, the snap ring 135is disposed in an annular groove formed in the opening 127 of thetrunnion [126]. Alternatively, as illustrated in FIG. 12, each of thetrunnions 126 ₁ and 126 ₂ of the carrier member 112 can be provided withan annular flange 180 radially inwardly extending from a distal end ofthe trunnion 126 ₁, 126 ₂ substantially perpendicular to the centralaxis 24. In this case, the axially outward travel of the integratedfluid-operated actuator/end cap assembly 164 is limited by the annularflange 180 engaging the actuator housing 130. Moreover, the actuatorhousing 130 to axle shaft [128] sliding interface is sealed by a lipseal 190 non-rotatably mounted to the actuator housing 130.

The vacuum-operated clutch actuator 164 further includes a spring member172 (such as a coil spring) disposed in the vacuum chamber 170 fornormally biasing the actuator piston 166 towards the first, engaged modeof the clutch collar 162. The annular spring-loaded actuator piston 166is provided with an actuator arm (or shift fork) 167 formed integrallywith the actuator piston 166 to drivingly engage the annular groove 166of the clutch collar 162 through a wear pad 183 for axially moving theclutch collar 162 into and out of driving engagement with the side gear[136]. Preferably, the actuator piston 166 and the actuator arm 167 aremade homogeneously as a single part member. Further preferably, the wearpad 183 is fabricated from a polymer material and is secured within thegroove 169 in the clutch collar 162 by any appropriate technique knownin the art, such as by adhesive bonding The actuator arm 167 is designedto mate with the groove 169 in the clutch collar 162.

The vacuum chamber 170 of the vacuum-operated clutch actuator 164 of thefirst and second clutch assemblies 160 ₁ and 160 ₂ communicates with asingle, suitable external vacuum source 182 via fluid passages 184 and185 formed through the carrier member 112 and the actuator housing 130,respectively, for connecting the vacuum-operated clutch actuator 164 tothe external vacuum source 182, such as the engine manifold through acontrol valve (not shown). The integrated actuator/end cap assembly 164communicates with the external vacuum source 182 through an externalfitting 186.

Operation of the drive axle assembly 110 incorporating the disconnectassembly [160] according to the second exemplary embodiment of thepresent invention is best understood by reference to FIGS. 9 and 10.

When a vacuum is not applied in the vacuum chamber 170 of thevacuum-operated clutch actuator 164, the actuator piston 166 is shiftedaxially inward toward the side gear [136], as shown in the FIG. 9, bythe coil spring 172. Consequently, the actuator arm 167 of the actuatorpiston 166 moves the clutch collar 162 so that the coupling teeth 165 ofthe clutch collar 162 mesh with (drivingly engage) the complementarycoupling teeth 151 of the side gear [136], thus placing the disconnectassembly [160] in the first, engaged mode, as illustrated in FIG. 9.Those skilled in the art would appreciate that in the engaged mode ofthe disconnect assembly [160], the side gear [136]is drivingly coupledto the axle shaft [128] through the clutch collar 162. In thisoperational mode, torque can be transmitted from the side gear [136] tothe output shaft [128] through the clutch collar 162.

Conversely, when a vacuum is applied in the vacuum chamber 170 of thevacuum-operated clutch actuator 164, the actuator piston 166 is shiftedaxially outward away from the side gear [136] against the biasing forceof the coil spring 172. Consequently, the actuator arm 167 of theactuator piston 166 moves the clutch collar 162 so that the couplingteeth 165 of the clutch collar 162 disengage from the complementarycoupling teeth 151 of the side gear [136], thus placing the disconnectmechanism [160] in the second, disengaged mode, as illustrated in FIG.10. Those skilled in the art would appreciate that in the disengagedmode of the disconnect mechanism [160], the side gear [136] is drivinglydisconnected from the output shaft [128]. In the disengaged mode, theoutput shaft [128] is rotationally independent lo from the side gear[136] and the other components of the differential assembly 114 and mayfreewheel independently of another output shaft [128]. Moreover, in thedisconnect mode, the side gear [136] may be stationary while the outputshaft [128] rotates due to tire rotation.

It should be noted that the changeover from the engaged mode to thedisengaged mode of the output shaft [128] or vice versa is quickly andconveniently accomplished remotely by means of an appropriate controlsystem associated with the vacuum-operated clutch actuator 164. Theactivating control for the vacuum-operated clutch actuator 164 may thusbe located in a cab of the vehicle within the driver's reach.

Therefore, the present invention provides a novel axle shaft disconnectassembly for a drive axle of a motor vehicle that utilizes conventionalcasting and machining processes for a carrier member, a differentialcase, and an axle shaft, thus significantly reducing capital and toolingrequirements to implement for production.

The foregoing description of the preferred embodiments of the presentinvention has been presented for the purpose of illustration inaccordance with the provisions of the Patent Statutes. It is notintended to be exhaustive or to limit the invention to the precise formsdisclosed. The embodiments disclosed hereinabove were chosen in order tobest illustrate the principles of the present invention and itspractical application to thereby enable those of ordinary skill in theart to best utilize the invention in various embodiments and withvarious modifications as suited to the particular use contemplated, aslong as the principles described herein are followed. This applicationis therefore intended to cover any variations, uses, or adaptations ofthe invention using its general principles. Further, this application isintended to cover such departures from the present disclosure as comewithin known or customary practice in the art to which this inventionpertains. Thus, changes can be made in the above-described inventionwithout departing from the intent and scope thereof. It is also intendedthat the scope of the present invention be defined by the claimsappended thereto.

1. A drive axle assembly comprising: a carrier member including anoutwardly extending trunnion having an opening therethrough; an outputshaft axially outwardly extending from said carrier member through saidopening in said trunnion; a differential assembly including adifferential case supported for rotation within said carrier member anda side gear being rotatably mounted about said output shaft; a clutchcollar disposed about said output shaft and non-rotatably coupledthereto and configured to selectively drivingly engage said side gear;and an clutch actuator mounted to said trunnion for axially moving saidclutch collar between a first position in which said clutch collardrivingly engages said side gear and a second position in which saidclutch collar is disengaged from said side gear.
 2. The drive axleassembly as defined in claim 15 further comprising a drive sleeverotatably mounted about said output shaft and non-rotatably coupled tosaid side gear; wherein said clutch collar configured to selectivelydrivingly engage said side gear through said drive sleeve.
 3. The driveaxle assembly as defined in claim 1, wherein said side gear has aplurality of axially outwardly directed coupling gear teeth, and whereinsaid clutch collar has axially inwardly directed coupling gear teethcomplementary to said axially outwardly directed coupling gear teeth ofsaid side gear.
 4. The drive axle assembly as defined in claim 1,wherein said clutch actuator is annular and coaxially and non-rotatablysecured within said trunnion of said carrier member so as to define anend cap in said opening in said trunnion.
 5. The drive axle assembly asdefined in claim 4, further comprising an expandable snap ring mountedto said trunnion so as to retain said annular clutch actuator withinsaid carrier member.
 6. The drive axle assembly as defined in claim 1,wherein said annular clutch actuator includes an end cap non-rotatablysecured to said trunnion and about said output shaft for covering saidopening in said trunnion.
 7. The drive axle assembly as defined in claim1, further comprising a shaft retention collar disposed about saidoutput shaft between said side gear and output shaft so that said sidegear is rotatably mounted about said shaft retention collar.
 8. Thedrive axle assembly as defined in claim 1, wherein said clutch actuatoris a fluid-operated clutch actuator including an annular actuatorhousing mounted to said trunnion coaxially therewith and defining afluid chamber and an annular actuator piston provided for axially movingsaid clutch collar between said first position and said second positiondepending on a fluid pressure within said fluid chamber.
 9. The driveaxle assembly as defined in claim 8, wherein said annular actuatorhousing of said first fluid-operated clutch actuator is non-rotatablysecured within said trunnion of said carrier member so as to define anend cap covering said opening in said trunnion.
 10. The drive axleassembly as defined in claim 9, further comprising an expandable snapring mounted to said trunnion so as to retain said actuator housingwithin said carrier member.
 11. The drive axle assembly as defined inclaim 8, further comprising an end cap non-rotatably secured to saidtrunnion and about said output shaft for covering said opening in saidtrunnion; said end cap defines said annular actuator housing of saidfluid-operated clutch actuator.
 12. The drive axle assembly as definedin claim 8, wherein said first fluid-operated clutch actuator includes aspring member normally biasing said actuator piston toward said firstposition.
 13. The drive axle assembly as defined in claim 8, whereinsaid actuator piston of said fluid-operated clutch actuator includes anactuator arm formed integrally therewith for drivingly engaging saidclutch collar.
 14. The drive axle assembly as defined in claim 1,wherein said drive axle assembly is an independent axle assembly.
 15. Adrive axle assembly comprising: a carrier member; an output shaftaxially outwardly extending from said carrier member; a differentialassembly including a differential case supported for rotation withinsaid carrier member and a side gear being rotatably mounted about saidoutput shaft; a drive sleeve rotatably mounted about said output shaftand non-rotatably coupled to said side gear; a clutch collar disposedabout said output shaft and non-rotatably coupled thereto and configuredto selectively drivingly engage said drive sleeve; and a clutch actuatorfor axially moving said clutch collar between a first position in whichsaid clutch collar drivingly engages said drive sleeve and a secondposition in which said clutch collar is disengaged from said drivesleeve.
 16. The drive axle assembly as defined in claim 15, wherein saidside gear has radially inwardly directed splines, wherein said clutchcollar has radially inwardly directed splines, and wherein said drivesleeve has first radially outwardly directed splines complementary tosaid radially inwardly directed splines of said side gear at an innerend thereof and second radially outwardly directed splines complementaryto said radially inwardly directed splines of said clutch collar at anouter end thereof.
 17. The drive axle assembly as defined in claim 15,wherein said drive axle assembly is an independent axle assembly.
 18. Adrive axle assembly comprising: a carrier member; an output shaftaxially outwardly extending from said carrier member; a differentialassembly including a differential case supported for rotation within bysaid carrier member and a side gear being rotatably mounted about saidoutput shaft; a shaft retention collar disposed about said output shaftbetween said side gear and said output shaft so that said side gear isrotatably mounted about said shaft retention collar; a clutch collardisposed about said output shaft and non-rotatably coupled thereto andconfigured to selectively drivingly engage said side gear; and anannular clutch actuator mounted to said trunnion for axially moving saidclutch collar between a first position in which said clutch collardrivingly engages said side gear and a second position in which saidclutch collar is disengaged from said side gear.
 19. The drive axleassembly as defined in claim 18, further comprising an elastomericO-ring mounted about said output shaft so as to be compressed betweensaid shaft retention collar and said output shaft in order to restrainrelative rotation between said shaft retention collar and said outputshaft.
 20. The drive axle assembly as defined in claim 19, wherein saidelastomeric O-ring is disposed in an annular groove formed in saidoutput shaft.
 21. The drive axle assembly as defined in claim 18,wherein said first shaft retention collar is non-rotatably mounted aboutsaid first output shaft.
 22. The drive axle assembly as defined in claim18, wherein said drive axle assembly is an independent axle assembly.